This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Seasonal and pandemic influenza A is a leading cause of infectious lung disease in the U.S. and worldwide. The most severe infections of influenza virus involve cells of the lower lung causing a viral pneumonia. One of the lung cell types that can be infected by influenza virus, alveolar macrophages, also play a role in the innate immune response to the infection. Cell proteins from infected alveolar macrophage will be systematically screened using a mass spectrometry based proteomics approach. Stable isotope labeling by amino acids in cell culture (SILAC) will be used to identify proteins that are differentially expressed in influenza virus infected cells compared to uninfected cells. Candidate differentially-expressed proteins from the mass spectrometry results will be validated by western blot analysis.